A curable composition has been improved in various ways taking account of the application, and widely used as a raw material for producing optical parts and formed articles, an adhesive, a coating material, and the like.
A curable composition has attracted attention as an optical element-securing composition (e.g., optical element adhesive and optical element sealing material) that is used when producing a sealed optical element.
Examples of the optical element include a light-emitting element (e.g., laser (e.g., semiconductor laser diode (LD)) and light-emitting diode (LED)), a light-receiving element, a hybrid optical element, an optical integrated circuit, and the like.
In recent years, an optical element that emits blue light or white light (i.e., an optical element that has a shorter emission peak wavelength) has been developed, and widely used. There is a tendency that a light-emitting element having a short emission peak wavelength is significantly increased in brightness, and the amount of heat generated by such an optical element further increases.
Along with a recent increase in brightness of an optical element, a cured product of an optical element-securing composition may deteriorate due to long-term exposure to high-energy light or high-temperature heat generated by such an optical element, whereby delamination or a decrease in adhesion may occur.
In order to solve the above problem, Patent Literature 1 to 3 propose an optical element-securing composition that includes a polysilsesquioxane compound as the main component.
However, the compositions and the cured products (e.g., members) disclosed in Patent Literature 1 to 3 may not exhibit sufficient heat resistance while maintaining sufficient adhesion.
Therefore, development of a curable composition that produces a cured product that exhibits excellent heat resistance and high adhesion has been desired.
Patent Literature 4 discloses a semiconductor light-emitting device member that is specified by (i) the chemical shift and the half-width of the peak observed in the solid-state Si nuclear magnetic resonance spectrum, (ii) the silicon content, and (iii) the silanol content.